1 files changed, 48 insertions, 13 deletions
diff --git a/src/mongo/db/session_catalog_mongod.cpp b/src/mongo/db/session_catalog_mongod.cpp
index fe77c218e91..ba5d503ebd8 100644
--- a/src/mongo/db/session_catalog_mongod.cpp
+++ b/src/mongo/db/session_catalog_mongod.cpp
@@ -38,6 +38,7 @@
 #include "mongo/db/create_indexes_gen.h"
 #include "mongo/db/dbdirectclient.h"
 #include "mongo/db/index_builds_coordinator.h"
+#include "mongo/db/internal_transactions_feature_flag_gen.h"
 #include "mongo/db/namespace_string.h"
 #include "mongo/db/operation_context.h"
 #include "mongo/db/ops/write_ops.h"
@@ -374,25 +375,59 @@ int removeExpiredTransactionSessionsFromDisk(
 }
 
 void createTransactionTable(OperationContext* opCtx) {
-    auto serviceCtx = opCtx->getServiceContext();
     CollectionOptions options;
-    auto createCollectionStatus =
-        repl::StorageInterface::get(serviceCtx)
-            ->createCollection(opCtx, NamespaceString::kSessionTransactionsTableNamespace, options);
+    auto storageInterface = repl::StorageInterface::get(opCtx);
+    auto createCollectionStatus = storageInterface->createCollection(
+        opCtx, NamespaceString::kSessionTransactionsTableNamespace, options);
+
     if (createCollectionStatus == ErrorCodes::NamespaceExists) {
-        return;
-    }
+        bool collectionIsEmpty = false;
+        {
+            AutoGetCollection autoColl(
+                opCtx, NamespaceString::kSessionTransactionsTableNamespace, LockMode::MODE_IS);
+            invariant(autoColl);
+
+            if (autoColl->getIndexCatalog()->findIndexByName(
+                    opCtx, MongoDSessionCatalog::kConfigTxnsPartialIndexName)) {
+                // Index already exists, so there's nothing to do.
+                return;
+            }
 
-    uassertStatusOKWithContext(
-        createCollectionStatus,
-        str::stream() << "Failed to create the "
-                      << NamespaceString::kSessionTransactionsTableNamespace.ns() << " collection");
+            collectionIsEmpty = autoColl->isEmpty(opCtx);
+        }
+
+        if (!collectionIsEmpty) {
+            // Unless explicitly enabled, don't create the index to avoid delaying step up.
+            if (feature_flags::gFeatureFlagAlwaysCreateConfigTransactionsPartialIndexOnStepUp
+                    .isEnabledAndIgnoreFCV()) {
+                AutoGetCollection autoColl(
+                    opCtx, NamespaceString::kSessionTransactionsTableNamespace, LockMode::MODE_X);
+                IndexBuildsCoordinator::get(opCtx)->createIndex(
+                    opCtx,
+                    autoColl->uuid(),
+                    MongoDSessionCatalog::getConfigTxnPartialIndexSpec(),
+                    IndexBuildsManager::IndexConstraints::kEnforce,
+                    false /* fromMigration */);
+            }
+
+            return;
+        }
+
+        // The index does not exist and the collection is empty, so fall through to create it on the
+        // empty collection. This can happen after a failover because the collection and index
+        // creation are recorded as separate oplog entries.
+    } else {
+        uassertStatusOKWithContext(createCollectionStatus,
+                                   str::stream()
+                                       << "Failed to create the "
+                                       << NamespaceString::kSessionTransactionsTableNamespace.ns()
+                                       << " collection");
+    }
 
     auto indexSpec = MongoDSessionCatalog::getConfigTxnPartialIndexSpec();
 
-    const auto createIndexStatus =
-        repl::StorageInterface::get(opCtx)->createIndexesOnEmptyCollection(
-            opCtx, NamespaceString::kSessionTransactionsTableNamespace, {indexSpec});
+    const auto createIndexStatus = storageInterface->createIndexesOnEmptyCollection(
+        opCtx, NamespaceString::kSessionTransactionsTableNamespace, {indexSpec});
     uassertStatusOKWithContext(
         createIndexStatus,
         str::stream() << "Failed to create partial index for the "